1. Field of the Invention
The present invention relates to a light emitting device having a plurality of light emitting cells and a package having the same mounted thereon, and more particularly, to a light emitting device having a plurality of light emitting cells, which form serial arrays on a single substrate and can be directly driven using an AC power source, and a package having the same mounted thereon.
2. Discussion of the Background
A light emitting diode is an electroluminescence device having a structure in which an n-type semiconductor of which major carriers are electrons and a p-type semiconductor of which major carriers are holes are joined together, and emits predetermined light through recombination of these electrons and holes. Such light emitting diodes are used as display devices and backlights, and their application area has expanded to the use thereof for general illumination while substituting the conventional incandescent bulbs and fluorescent lamps.
A light emitting diode consumes less electric power and has a longer service life as compared with conventional light bulbs or fluorescent lamps. The electric power consumption of a light emitting diode is less than a few tenth to a few hundredth of those of conventional illumination devices, and the life span thereof is several to several ten times, thereby having reduced electric power consumption and excellent durability.
To use such light emitting diodes for illumination, it is necessary to effectively dissipate heat produced from light emitting devices to the outside. Accordingly, interest in flip-chip type light emitting devices capable of effectively dissipating heat produced from the light emitting devices to the outside is increasing.
FIG. 1 is a sectional view illustrating a conventional flip-chip type light emitting device 20.
Referring to FIG. 1, first and second electrodes 12 and 14 are formed on a predetermined substrate 10, e.g., a submount substrate or a lead frame, and solders 22 and 24 are formed on these electrodes. Then, a light emitting device 20 is bonded on the substrate 10. At this time, a P-type semiconductor layer and an N-type semiconductor layer of the light emitting device 20 are bonded to the respective solders. Thereafter, the substrate 10 with the light emitting device 20 bonded thereon is encapsulated.
Such conventional flip-chip type light emitting devices have higher heat dissipation efficiency as compared with other light emitting devices using bonding wires, and have improved optical efficiency because little light is shielded. Further, the flip-chip type light emitting devices have an advantage in that their packages can be compacted because they do not use bonding wires.
However, since such a light emitting device is repeatedly turned on and off depending on the phase of an AC power source, there is a problem in that the light emitting device may be easily damaged. Accordingly, it is difficult to use a light emitting device for the purpose of general illumination by connecting it directly to a household AC power source.